Solenoid operated devices are in widespread use, including applications wherein it is highly important for supervisory personnel to know whether the device being actuated actually responds to energization or deenergization of the related solenoid. Various expedients have been resorted to heretofore to acknowledge such operation but these require a communication facility separate from and in addition to the power supply circuit for the solenoid. Such separate communication devices include electrical, pneumatic and/or hydraulic expedients subject to obvious shortcomings and disadvantages avoided by this invention.